The Study On The Characteristics Of Nickel And Vanadium In Blend Crude Oil

During the process of petroleum genesis, environmental redox potental, pH and sulfur activity can affect the Ni/V of various crude oil origin. Nickel and vanadium mainly exist as stable organic chelates in the oil. The role of weahtering to the nickel, vanadium content and Ni/V is weak. So it is an important significance to study nickel and vanadium characteristics of crude oils for the distinguish oils. But the identification of oil spill mostly study the characteristics of single crude oil, yet, while the study on the characteristics of blend crude oil is extremely few. Therefore, nickel and vanadium characteristics of blend crude oil was discussed in this paper, in order to provide a technical support for the oil spill distinguishing.Five knids of domestic and international crude oils were used as study object, such as UAE, Iraq, Saudi Arabia, Malaysia, Daqing Preceding deal with crude oil samples by crucible ashing, the content of nickel and vanadium in oil was determined by graphite furnace atomic absorption spectrometry(GF-AAS), then Ni/V was figured out. The content of nickel and vanadium, Ni/V were available as variables in the similarity analysis for five kinds of crude oil. According to the result of similarity analysis, four groups of blend oil such as UAE-Iraq, Daqing-Malaysia, Daqing-Saudi Arabia, Malaysia-Saudi Arabia have been regarded as samples before weathering, and the influence of blending ratio on the characteristics of nickel and vanadium in the crude oil was investigated. Then, a group of UAE-Iraq which nickel and vanadium characteristics were similar and a group of Daqing-Saudi Arabia which nickel and vanadium characteristics were different, and they were selected for the two period weathering experiments. Each period was 30 days. The influence of different weathering condition on the characteristics of nickel and vanadium in the crude oil was discussed. The experimental results as follows:1. The influence of blending ratio on the characteristics of nickel and vanadium.With the ratio of single oil whose Ni/V was higher increasing, the Ni/V in blend oil were also growing. If two isofacial crude oil were blended, the characteristics of Ni/V in blend crude oil remain unchanged. For example, a group of UAE-Iraq in which two kinds of single crude oil were marine facies. A group of Daqing-Malaysia in which two kinds of single crude oil were continental facies. If two heteropical crude oil were blended, according to the proportion of each kind of single oil to judge the facies of blend crude oil, such as Malaysia-Saudi Arabia, Daqing-Saudi Arabia. Using the content of nickel and vanadium, Ni/V as variables, the blend oil with different mixing proportion could be distinguished by systematic cluster analysis. The characteristics of nickel and vanadium in the blend oil in which one kind of single oil with dominate proportion was similar and could classify into the same cluster easily.2..The influence of weathering on the characteristics of nickel and vanadium.The Ni/V of UAE-Iraq and Daqing-Saudi Arabia whose Ni/V showed little change during their weathering had strong resistance to weathering. The Ni/V characteristics of UAE-Iraq which two kinds of single oil had the same facies was not influenced by weathering, and still kept the properties of marine crude oil; the Ni/V characteristics of Daqing-Saudi Arabia which two kinds of single oil had different facies was little changed by weathering, such as 2:1 in Daqing-Saudi Arabia whose Ni/V was close to 1 before weathering, and was slightly larger than 1 after weathering, this blend oil shows the property of continental crude oil. The cluster’s situation of two kinds of blend oil had changes in the weathering process, but the blend oils in which one kind of single oil with dominate proportion were easily classified into the same cluster, and this characteristics was not influenced by weathering.